The invention concerns a tank filling nipple of the type connectable with a tank filling pipe with a closure flap arranged inside of the mounting nipple for movement between a closed position at which it engages a sealing seat and an open position at which it is lifted from the sealing seat and with a duct branching from the mounting nipple behind the sealing seat in the filling direction, in which duct an overfill valve operable by the adjustable closure flap is arranged, which overfill valve is closed upon opening of the closure flap, and also including an automatically opening overpressure valve.
In the construction of modern automobiles it is becoming more and more common to apply a filling nipple to the end of the tank filling pipe, which nipple unifies several different functions. Such tank filling nipples generally contain a self-closing closure, which for example may be formed as a closure flap movable in the interior of the tank filling nipple and biased in the direction toward a sealing seat, and which closure flap is movable by the dispensing nozzle to its open position.
A tank filling nipple of the type mentioned in the preamble of claim 1 is already known from DE 37 2-1 049 A1. This nipple is provided with a duct branching from the mounting nipple from behind the sealing seat in the filling direction, and in which duct is arranged an overfill valve operable by the movable closure flap. This overfill valve is open when the closure flap is closed so that in the case of warming the expanding fuel can overflow through this duct into a compensating container. This overfill valve is coupled with the closure flap so that it is closed when the closure flap is opened to avoid an overflow of the fuel into the compensating container. This solution is relatively expensive since in addition to the main tank a separate compensating container must be provided which moreover in a non-described way must be connectable with the main tank in order that the overflown fuel eventually can flow back into the main tank.
Moreover, the known tank filling nipple is provided with an underpressure valve which automatically opens upon an overpressure in the tank so that a pressure compensation can take place. This overpressure valve is arranged on the closure flap with these parts being of complicated construction, heavy and bulky, so that difficulties can arise in the application of the closure flap to the interior of the tank filling nipple, and also the support as well as the return spring for the closure flap must suit its construction weight and size. Also there exists the danger that the overpressure valve which connects with the upper side of the closure flap may be damaged by the insertion of the dispensing nozzle, which damage generally makes necessary a replacement of the entire tank filling nipple.
A further disadvantage of the known construction occurs in the following way: the overfill valve operated by the closure flap is necessarily arranged by the involved construction directly below the sealing seat of the closure flap so that the overflow level also is positioned directly below the closure flap which no longer meets the intended safety requirements. It is much more desired that the highest possible fill level in the normal position of the vehicle be positioned a given amount below the sealing seat.
To assure a trouble-free flow of the fuel from the tank during normal motor operation the tank must also be provided with a ventilating valve which moreover at a given predetermined inclined position of the vehicle, or upon a turning over of the same, must automatically close to, for example in the case of an accident, prevent dangerous discharge of the fuel. Such ventilating valves are generally provided by the tank manufacturer since previously no possibility appeared to apply these in the region of the closure flap similarly to the overpressure valve. Therefore, in the manufacture of vehicles it has generally been necessary to have two separate assembly processes for the ventilating valve on one hand and for the tank filling nipple on the other hand which with the large numbers and short assembly times of modern motor vehicles can amount to considerable assembly costs.
The object of the present invention is to provide a tank filling nipple of the type mentioned in the preamble of claim 1 which with regard to simple construction and reliable function fulfills all desired operating and safety requirements and which in comparison to the functioning of known devices can include additional functions so that some assembly processes in the construction of tanks can be spared.